1. Field of the Invention
The present invention relates to electrical connectors for flexible boards.
2. Description of the Related Art
Japanese patent application Kokai No. 9-283235 discloses an electrical connector of this type.
As FIG. 5 shows, this connector comprises a housing 53 and at least one first terminal 51 and at least one second terminal 52, both of which are made by stamping a metal sheet and spaced at intervals in a first direction perpendicular to the picture plane. The first terminal 51 has a support arm 54, a contact arm 55, a fixing arm 56, and a connection leg 57 provided in this order from top. The support arm 54 is made wide and rigid and has a substantially circular bearing section 54A at the front end. The contact arm 55 is made elongated and flexible and has a contact section 55A. The fixing arm 56 has an engaging projection 56A. The connection leg 57 extends through the housing to a circuit board P. The first terminal 51 is inserted into a first slot of the housing 53 from the right, and the engaging projection 56A lock it in place.
The second terminal 52 is identical with the first terminal 51 except that it has no fixing arm 56. It is inserted into the housing 53 from the left, and the connection leg 58 extends to the left. The first and second terminals 51 and 52 are inserted alternately in opposite directions such that the contact sections 55A and 59A are arranged in a zigzag fashion as viewed from the top. The bearing sections 54A of terminals 51 form a shaft that extends in the first direction and supports a pressure member 60 for rotation. The pressure member 60 is turned counterclockwise (F2) at a concave face 61 to a closed position where a pressure section 62 presses a flexible board 70 downwardly. The flexible board 70 has a reinforced section 71 and a circuit section 72 provided on the lower face of the reinforced section 71.
In use, the pressure member 60 is turned clockwise (F1) about the bearing sections 54A so as to provide a large space above the contact arms 55, into which the flexible board 70 is inserted from the left such that the circuit section 72 are placed on the contact sections 55A and 59A.
Then, the pressure member 60 is turned counterclockwise (F2) to the closed position so that the flexible board 70 is pressed down by the pressure section 62 of the pressure member 60, bringing the circuit section 72 into spring contact with the contact sections 55A and 59A for electrical connection.
There is a demand for a low-profile connector for miniaturizing the electronic equipment.
However, the connector has a large number of terminals, and the pressure member has a large width so that when it is turned to the closed position, the reactive force of the terminals warps and disengages the pressure member from the bearing sections. In order to prevent such disengagement, the pressure member has been made thick, resulting in the tall connector.
In addition, the contact sections of the first and second terminals are spaced in the second or horizontal direction so that in order to effectively press the flexible board against both the first and second contact sections, it is desired for the bearing sections to spaced far from the contact sections, leading to the even thicker pressure member.
Accordingly, it is an object of the invention to provide a low-profile connector with a thin pressure member that is able to effectively press down the flexible board against the first and second terminals spaced apart.
According to one aspect of the invention there is provided a flexible board electrical connector which comprises a housing having an open mouth; at least one first terminal provided in the housing and having an first upper arm and a first lower arm with an upwardly extending first contact section; at least one second terminal provided in the housing and having a second upper arm and a second lower arm with an upwardly extending second contact section; a pressure member having first and second bearing sections that engage lower and upper edges of the first and second upper arms, respectively, for rotation between an open position where a flexible board is inserted through the open mouth such that a circuit face of the flexible board is placed on the first and second contact sections and a closed position where the flexible board is pressed against the first and second contact sections.
Since the pressure member is held between the first and second upper arms of the first and second terminals, it is possible to prevent the thin pressure member from falling from the housing. The first upper arm of the first terminal is made flexible so that it is flexed upwardly by the first bearing section when the pressure member is turned from the open position to the closed position while the pressure member is moved downwardly by a reactive force of the upper arm. Thus, the reactive force moves the pressure member downwardly to press down the flexible board so that the contact pressure for the second terminal is secured.
The upper arm of the second terminal is made flexible so that when the pressure member is moved downwardly, it is flexed downwardly by the second bearing section to thereby press down the flexible board. Consequently, the second upper arm of the second terminal presses down the flexible board so that the flexible board is brought into contact with the first and second contact sections ever if the first and second contact sections are spaced apart in the flexible board insertion/removal direction. The upper and lower arms of the second terminal are joined together by a linking section from which an engaging projection extends and engages an engaging hole of the housing with a play so that a part of the lower arm is flexed when the upper arm is flexed. This increases the degree of flexure and reduces the height of a connector.
The first and second contact sections of the first and second terminals are spaced apart in the flexible board insertion/removal direction. The distance between a center of rotation and a contact point between the pressure member and the flexible board becomes smallest at the closed position of the pressure member, keeping the pressure member at the closed position against the reactive force of the terminals, preventing the pressure member from falling by the reactive force.
When the pressure member is turned to the open position, at least one of the first and second bearing sections flexes upwardly the first and second upper arms of the first and second terminals to thereby increase a distance between the upper and lower arms. Consequently, the flexible board can be inserted into or removed from the housing with a zero insertion/removal force.
According to another aspect of the invention there is provided a flexible board electrical connector, wherein the upper and lower arms of the second terminal are joined together by a linking section from which an engaging projection extends and engages an engaging hole of the housing with a play so that a part of the lower arm is flexed when the upper arm is flexed.
Since both the upper arm and a part of the lower arm are flexed, a large amount of flexure is obtained, making it possible to reduce the height of the connector by that much.
According to still another aspect of the invention there is provided a flexible board electrical connector which, unlike the first and second terminals according to the first and second aspects of the invention, comprises a single type of terminals that hold the pressure member between them at the closed position, thereby producing the same results. The pressure member having first and second bearing sections that engages lower and upper edges of the upper arms for rotation.
According to the fourth aspect of the invention, a single type of terminals enables to insert or remove the flexible board with a zero-insertion/removal force.
According to the fourth aspect of the invention there is provided a flexible board electrical connector which comprises a pressure member having at least one bearing section that engages lower edge of the upper arm for rotation to flex upwardly the upper arm, making a distance between the upper and lower arms largest at the open position.